[0001] The present invention relates to a unit to form pellet elements.
[0002] It is known that in many industrial processes for example in the chimical and foodstuff
fields, the production cycle includes the formation of pellet elements starting from
materials which are kept to the fluid state, that is the formation of substantially
ball-shaped portions which are transferred and solidified on suitably-cooled conveyor
belts.
[0003] In some cases the material thus fractionated may be an intermediate product adapted
to further workings, but in other cases it already constitutes a final product.
[0004] Said pellet elements are made using various apparatus which substantially can be
divided into two different types.
[0005] One type of known apparatus involves a series of dispensing nozzles located above
the conveyor belt and transversely thereto, which continuously dispense predetermined
amounts of material in the form of drops falling onto the conveyor belt surface. This
type of apparatus however has serious drawbacks in that the static delivery of the
fluid material onto a moving conveyor belt brings about an important deformation of
the falling drops. Actually the drops will tend to take an elongate form losing their
substantially ball-shaped conformation. In addition, depending upon the viscosity
of the material and the conveyor belt feed speed, the separation between subsequent
pellets delivered from the same nozzle may not occur.
[0006] In order to overcome the drawbacks encountered with this type of apparatus attemps
have been made to use a second type of apparatus in which the drops of material are
practically distributed onto the conveyor belt by means of movable dispensing holes
moving at the same speed as the feed speed of the conveyor belt. This second type
of apparatus generally comprises one fixed feeding cylinder the axis of which is transverse
to the feed direction of the conveyor belt and which exhibits a number of feed holes
along the generatrix of the feeding cylinder itself, at the lowest position thereof.
Provided externally and in contact with the feeding cylinder is a second coaxial dispensing
cylinder, the peripheral rotational speed of which is substantially coincident with
the feed speed of the conveyor belt. Such second dispensing cylinder has a number
of suitably spaced apart delivery holes which come in register with the feed holes
of the first cylinder and therefore enable the issue of drops of material to the fluid
state which do not lose their ball-shaped configuration even when they come in contact
with the conveyor belt due to the absence of relative speed between said belt and
the delivery holes.
[0007] But also this second type of known apparatus has limits and serious drawbacks, although
it produces pellet elements of a satisfactory quality.
[0008] Actually these known apparatus are of complex and delicate construction and therefore
expensive, due to the high precision required in coupling the inner static cylinder
to the outer movable one. In addition, if in operation a partial ovalization of one
cylinder occurs, the apparatus becomes useless and therefore must be replaced. They
also have poor operative flexibility since they are provided with delivery holes spaced
apart according to a fixed pitch. Therefore, the amount of fluid material used being
equal, it is possible to accomplish pellet elements having only one and the same size.
[0009] It is not even possible to adjust the apparatus operation to the varying viscosities
of the materials to be made into pellets. If one wishes to make the production of
pellet elements suit the different types of fluid materials or make it meet different
size requirements, it is necessary to replace the dispensing cylinder, which involves
high costs also due to the down time as a result of the needed replacement.
[0010] Under this situation the technical task underlying the present invention is to provide
a unit to form pellet elements capable of substantially eliminating the above drawbacks.
[0011] Within the scope of this technical task it is an important object of the invention
to provide a unit to form pellet elements which is very flexible in operation as regards
both the possibility of producing said pellet elements in different varying sizes
and the type and viscosity of the material to the fluid state which can be used.
[0012] Another important object of the invention is to provide a unit to form pellet elements
which is of simple and easy construction and reduced production costs.
[0013] A still further object of the invention is to provide a unit to form pellet elements
which makes the necessary servicing operations much more easier.
[0014] Yet another object of the invention is to provide an embodiment of the invention
which is advantageous in itself while representing a technical progress in the specific
field.
[0015] The technical task and the objects mentioned above, and still further objects which
will become more apparent in the following are substantially attained by a unit to
form pellet elements including a conveyor belt adapted to receive, transfer and cool
said pellet elements, characterized in that it comprises a cylindrical member disposed
above said belt and rotatable about an axis transverse to the feed direction of the
conveyor belt, said cylindrical member having a peripheral speed substantially corresponding
to the feed speed of the belt, at least a ring element engaged in coaxial relation
with and at the outside of said cylindrical member and provided with a number of projections
oriented radially apart from said cylindrical member, feed members and dispensing
members adapted to distribute material to the fluid state onto said projections and
to form drop portions of the same thereon, each of said projections passing in the
vicinity of the belt so as to let one of the drop portions defining one of said pellet
elements fall thereon.
[0016] Further features and advantages of the invention will best be understood from the
detailed description of a preferred embodiment of a unit to form pellet elements according
to the invention, given hereinafter by way of non-limiting example with reference
to the accompanying drawings, in which:
- Fig. 1 is an elevation side view partly in section of a unit in accordance with
the invention;
- Fig. 2 is a fragmentary section of the unit carried out along line II-II in Fig.
1;
- Fig. 3 shows, to an enlarged scale, a construction detail of the unit of the invention
according to a second embodiment thereof.
[0017] Referring to the drawings, the unit to form pellet elements according to the invention
has been generally identified by reference numeral 1. It comprises a cylindrical member
2 supported by a shaft 3 rotating about an axis 4 transverse to the feed direction
of a conveyor belt 5. The belt, of known type and located underneath the cylindrical
member 2, has a support table 5a made of metal under which cooling means 5b of known
type is located. Provided in coaxial relation with the cylindrical member 2 and at
the outside of the same are ring elements 6 disposed alongside each other but spaced
apart by spacers 7. Through holes suitably bored in the ring elements 6 and spacers
7 are crossed by rods 8 which enable both these elements to be clamped pack-wise.
Each ring element 6 exhibits a number of equidistant projections 9 extending radially
substantially in the form of a tooth with triangular profile. Therefore the ring element
6 and the related projections 9 taken as a whole define a ring gear 10.
[0018] The shaft 3 is supported by a pair of bearings 11 mounted on fixed guides 11a and
vertically movable, being acted upon by fluid-operated cylinders or the like, in order
to allow the position of projections 9 to be suitably adjusted so that said projections
may pass in the vicinity of the conveyor belt 5.
[0019] Provision is also made for feed means 12 disposed externally to the ring gears 10
and spaced apart therefrom, being located at an upper region of the cylindrical member
2. The feed means 12 comprises a dispensing device 13, defined for example by a tube-shaped
element through which material to the fluid state, used to form pellet elements, is
caused to flow.
[0020] The tube-shaped element exhibits, at the lower part thereof, a series of delivery
holes 13a aligned along a direction parallel to a generatrix of the cylindrical member
2. In this manner the dispensing device 13 ejects material to the fluid state according
to said direction and the material falls down close to each ring gear 10. Dispensing
means 14 is located under the feed means 12 and comprises a spatula-shaped element
15 extending parallelly to axis 4. The spatula-shaped element 15 has an indentation
16 partly matching the shape of the projections 9 and comprising ridges 17 and notches
18. Ridges 17 are substantially in contact with spacers 7 and notches 18 surround
projections 9 leaving empty spaces in the region of the tips of said projections.
In this manner the indentation 16 is adapted to move the material present at the base
of the projections 9 and on spacers 7, into said empty spaces where drop portions
of the material are formed. Feed means 12 and dispensing means 14 are engaged to the
bearing 11 by means of adjustable positioning members 19 comprised of a support guide
20 in the form of an arc of a circle concentric with axis 4 and positioning screws
21 slidable within elongated holes 21a provided in the support guide 20.
[0021] Projections 9 can be accomplished in a second embodiment 9a shown in fig. 3. In this
case they are comprised of a sleeve 22 engaged to the ring element 6, a plug 23 radially
slidable within the sleeve 22 and a counterspring 24 tending to make the plug 23 elastically
emerge from sleeve 22. When the plug 23 is brought into contact with the conveyor
belt 5, said belt counteracts the action of spring 24 and tends to make the plug 23
retreat.
[0022] Provision is finally made for heating means designed to keep in the liquid state
the fluid material used to form said pellet elements and disposed outside and inside
the cylindrical member 2. Said heating means comprises circuits 25 through which suitable
heating fluids circulate within the cylindrical member 2 and a dome-shaped element
26 surrounding the cylindrical member at least partially.
[0023] Operation of the unit to form pellet elements described above mainly as regards structure,
is as follows.
[0024] After arranging the selected gear rings 10 (the number and type of which must correspond
to the production requirements) on the cylindrical member 2, the cylindrical member
itself is driven in rotation in known manner and to a peripheral speed corresponding
to the feed speed of the conveyor belt 5. The material to the fluid state which is
wished to be fractionated into pellet elements is caused to flow into the dispensing
device 13 from which it descends by gravity wetting the projections 9 and spacers
7. When the projections 9 pass close to the indentation 16 of the spatula-shaped element
15, the material is moved to the tip of said projections where at each tip a drop
is formed due to the known phenomena linked to the surface tension of the liquid.
[0025] As each projection 9 passes in the vicinity of the conveyor belt 5, the drop of material
carried by the projection itself tends to detach by gravity and it is captured by
the upper metal surface of the belt. Orderly raws of pellet elements are therefore
formed on the conveyor belt and while moving forward they solidify, also due to the
presence of cooling means located underneath the conveyor belt.
[0026] According to requirements, it is possible to replace the gear rings 10 provided with
equidistant projections having a given pitch with other gear rings having different
circumferential pitches. If for example the pitch is reduced and the rotational speed
remains unchanged, there is an increase in the frequency of passage of the projections
under the feed means 12 and therefore a decrease in the amount of material to the
fluid state dispensed onto each projection. Therefore the drop sizes of the next pellet
elements become smaller.
[0027] It is also possible to modify the distance between the ring gears 10 transversely
to the feed direction of the conveyor belt 5 by changing spacers 7, or to stagger
the positions of the projections between adjacent ring gears. In this manner the pellet
elements can be dropped onto the conveyor belt 5 according to varying positions.
[0028] Furthermore, the feed means 12 and dispensing means 14 can be located at different
distances from the conveyor belt 5 by acting on the positioning members 19. For example,
if the fluid material has a low viscosity it is convenient to locate the feed means
12 closer to the top of the cylindrical member 2 so that the greater length travelled
over said member may compensate for the excessive slip velocity.
[0029] Finally in case of materials having a high viscosity it is possible to replace the
ring gears 10 having triangular tooth-shaped projections 9 with rings the projections
9a of which are of the type shown in Fig. 3. In this case the material to the fluid
state wets the plug 23 which is at its outermost projecting position due to the action
of the counterspring 24. When each projection 9a has come into contact with the conveyor
belt 5, said belt tends to make the plug 23 retreat and the detachment of the material
from the outer surface of the plug 23 itself is facilitated.
[0030] The invention attains the intended purposes and achieves important advantages.
[0031] In particular it will be noted that the easy interchangeability of the ring gears
10 makes their use particularly flexible and adaptable to every production process.
[0032] In addition, the material to the fluid state wets the cylindrical member 2 only externally
and therefore its cleaning and servicing is much easier.
[0033] Finally it will be recognized that the particular embodiment shown is also advantageous
in its specific aspects which are apparent from the specification and drawings.
[0034] The invention as conceived is susceptible of many modifications and variations, all
of them falling within the scope of the inventive idea. All of the details can be
replaced by technically equivalent elements. In the practical accomplishment of the
invention the materials, forms and sizes can be of any nature and magnitude, according
to requirements.
1. A unit to form pellet elements, including a conveyor belt (5) adapted to receive,
transfer and cool said pellet elements, characterized in that it comprises:
- a cylindrical member (2) disposed above said belt (5) and rotatable about an axis
(4) transverse to the feed direction of the conveyor belt (5), said cylindrical member
(2) having a peripheral speed substantially corresponding to the feed speed of the
belt (5),
- at least a ring element (6) engaged in coaxial relation with and at the outside
of said cylindrical member (2) and provided with a number of projections (9) oriented
radially apart from said cylindrical member (2),
- feed members (12) and dispensing members (14) adapted to distribute material to
the fluid state on said projections (9) and to form drop portions of the same thereon,
each of said projections (9) passing in the vicinity of the belt (5) so as to let
one of the drop portions defining one of said pellet elements fall thereon.
2. A unit according to claim 1, characterized in that provision is made for a number
of said ring elements (6) adapted to be disposed alongside each other and at predetermined
mutual distances.
3. A unit according to claim 2, characterized in that spacers (7) interposed between
said ring elements (6) are provided, which are designed to define said mutual distances.
4. A unit according to claim 3, characterized in that provision is further made for
locking tie rods (8) crossing said ring elements (6) and spacers (7) and adapted to
clamp both said ring elements and spacers pack-wise.
5. A unit according to claim 1, characterized in that said projections (9) are disposed
along the circumferential outline of said ring element (6), being spaced apart from
each other by the same distance.
6. A unit according to claim 1, characterized in that said feed means 12 comprises
a dispensing device (13) adapted to continuously dispense said material substantially
to the fluid state according to a delivery direction parallel to a generatrix of said
cylindrical member (2) so that said fluid material may be dropped at least in the
vicinity of said at least one ring element (6).
7. A unit according to claim 1, characterized in that said dispensing means (14) is
disposed below said feed means (12) and comprises a spatula-shaped member (15) extending
parallelly to the axis of said cylindrical member (2) and exhibiting an indentation
(16) partly matching the shape of said projections (9) so as to be substantially in
contact with base areas of said projections (9), said indentation (16) being adapted
to move said fluid material to the tips of said projections (9) in order to form said
drop portions.
8. A unit according to claim 1, characterized in that adjustable positioning members
(19) are provided for said feed means (12) and dispensing means (14) which are adapted
to make these means take a number of positions differently spaced apart from said
conveyor belt (5).
9. A unit according to claim 5, characterized in that said projections (9) substantially
extend in the form of a tooth with triangular profile and define a ring gear (10)
together with said ring element (6).
10. A unit according to claim 1, characterized in that each of said projections (9a)
comprises:
- a sleeve (22) integral with said ring gear,
- a plug (23) radially slidable in said sleeve (22),
- a counterspring (24) adapted to make the plug (23) elastically emerge from said
sleeve (22), said plug (23) being pushed to the inside of the sleeve when it comes
in contact with said conveyor belt (5).
11. A unit according to claim 1, characterized in that heating means (25, 26) is provided
inside and outside said cylindrical member (2), which is adapted to keep said fluid
material in the liquid state.